Heretofore, U.S. patents on combined vehicle vent and escape hatches, such as Manning U.S. Pat. Nos. 4,021,073, 4,412,404 and 4,433,506 and Kelly et al U.S. Pat. No. 4,519,645, have each had a cover or door hinged to opposite sides of a frame and depended on the separability of parts of one of the hinges for enabling the cover, as an escape hatch, to be swung to full open position about the other hinge. The problem common to these patents is that their separable hinges are adapted to be separated into parts when their covers are in closed position and in that position the covers are not swingable to full open position about the opposite hinge. It is to solving this problem that the present invention is directed.